The invention relates to a hydraulic control system for supplying pressure fluid to at least one consumer.
For example, U.S. Pat. No. 5,138,838 A has disclosed a control system of this kind. In this control system, a consumer, for example a differential cylinder, is supplied via a valve device with pressure fluid that is furnished by a pump. The supply to the consumer and the return from it each contain a respective continuously adjustable directional control valve. In their neutral positions, the directional control valves are prestressed into a closed position and, by means of pressure reduction valves, can each be moved in one direction in which the pump is connected to the associated pressure chamber and in another direction in which the respective associated pressure chamber is connected to the tank. In this known control system, through suitable triggering of the two directional control valves, the consumer can be operated with a so-called regeneration circuit. For example, when a cylinder travels outward, the contracting annular chamber is connected via the associated directional control valve to the pressure fluid inlet of the expanding annular chamber so that the cylinder is extended in a rapid movement. A disadvantage of the regeneration/differential circuit, however, is that due to the restraining of the consumer (effective area corresponds to the piston rod area with equal pressures in the annular chamber and cylinder chamber), the consumer cannot be operated with the maximum output.
A control system of this kind also requires a relatively high apparatus complexity since the directional control valves are embodied in the form of 3-position valves and a respective pressure reduction valve must be provided for each movement direction.